Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO2 concentrations

Nature Geoscience
By: , and 

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Abstract

During the last deglaciation (19,000–9,000 years ago), atmospheric CO2increased by about 80 ppm. Understanding the mechanisms responsible for this change is a central theme of palaeoclimatology, relevant for predicting future CO2 transfers in a warming world. Deglacial CO2 rise hypothetically tapped an accumulated deep Pacific carbon reservoir, but the processes remain elusive as they are underconstrained by existing tracers. Here we report high-resolution authigenic neodymium isotope data in North Pacific sediment cores and infer abyssal Pacific overturning weaker than today during the Last Glacial Maximum but intermittently stronger during steps of deglacial CO2 rise. Radiocarbon evidence suggestive of relatively ‘old’ deglacial deep Pacific water is reinterpreted here as an increase in preformed 14C age of subsurface waters sourced near Antarctica, consistent with movement of aged carbon out of the deep ocean and release of CO2 to the atmosphere during the abyssal flushing events. The timing of neodymium isotope changes suggests that deglacial acceleration of Pacific abyssal circulation tracked Southern Hemisphere warming, sea-ice retreat and increase of mean ocean temperature. The inferred magnitude of circulation changes is consistent with deep Pacific flushing as a significant, and perhaps dominant, control of the deglacial rise of atmospheric CO2.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO2 concentrations
Series title Nature Geoscience
DOI 10.1038/s41561-018-0205-6
Volume 11
Year Published 2018
Language English
Publisher Nature
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 7 p.
First page 749
Last page 755